Carroll, David

Contact Information

Research & Project Interests

Our lab is interested in the molecular mechanisms that regulate oocyte maturation and fertilization. Sperm-egg fusion initiates a transient increase in the concentration of cytoplasmic calcium in the egg. This increase is a fundamental process that occurs in the eggs of all the organisms that have been studied and it is critical for activating the egg to begin development. Incredibly, the molecular mechanism that links the sperm-egg interaction to the initiation of this calcium increase is only now beginning to be understood.

Our research focuses on the role of a particular enzyme called phospholipase C gamma (PLCg). PLCg is a member of a larger class of cytoplasmic enzymes called phospholipases. These enzymes function to produce two signaling messenger molecules called diacylglycerol and inositol 1,4,5-trisphosphate from membrane phospholipids. They function in many cell types, including nerves, muscles and immune cells.

Current Research

Using a combination of biochemistry, molecular biology and live cell microscopy, we have discovered that PLCg is required for the initiation of the calcium increase during fertilization in starfish and sea urchin eggs. In collaboration with Dr. Kathy Foltz of the University of California at Santa Barbara and Dr. Laurinda Jaffe of the University of Connecticut Health Center, we have cloned a starfish PLCg cDNA from an arrayed oocyte cDNA library. We are currently using this clone as a tool to look for proteins that interact with PLCg in a fertilization-specific manner. We have determined that there are a suite of tyrosine-phosphorylated proteins, some from the sperm and some from the egg, that bind to PLCg only after fertilization. The identification of these proteins is a major goal of the laboratory in the coming years. Two graduate students from the laboratory (Leia Shuhaibar and Lu Zhong) have also developed a method for the visualization of changes in an enzyme called Mitogen-activated Protein Kinase (MAPK) using single cells. This allows us to gain a better understanding of the regulation of this enzyme during oocyte maturation and fertilization.